The three plaintiffs allege that Zuckerberg once worked with them on a similar wbsite now known as ConnectU. According to the lawsuit, Zuckerberg took proprietary source code and other material from that site to create Facebook.

"So, he basically did what you could call a brain drain and kind of took off with it under our noses," said Cameron Winklevoss in an interview with Canada's CTV News.

The plaintiffs first learned about Zuckerberg's new project in a Harvard newsletter, and then immediately kicked him out of their online project. Since then, however, Facebook has grown to become the second most popular social networking site in the US.

The suit was originally filed in 2004 and is just now making its way to court. The legal battle will begin tomorrow.